package com.ruoshui.rpc.util.json;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 *
 * @Author: RuoShui
 * @Date: 2022/9/16 11:14
 * @Description: JsonReader的父类
 **/
public class BasicJsonReader {
	private static Logger logger = LoggerFactory.getLogger(BasicJsonwriter.class);


	/**
	 *
	 * @param json 类型{}
	 * @return 将JSON转换为Map
	 */
	public Map<String, Object> parseMap(String json) {
		if (json != null) {
			json = json.trim();
			if (json.startsWith("{")) {
				return parseMapInternal(json);
			}
		}
		throw new IllegalArgumentException("Cannot parse JSON");
	}

	/**
	 *
	 * @param json []
	 * @return 将Json数组转换为List集合
	 */
	public List<Object> parseList(String json) {
		if (json != null) {
			json = json.trim();
			if (json.startsWith("[")) {
				return parseListInternal(json);
			}
		}
		throw new IllegalArgumentException("Cannot parse JSON");
	}

	/**
	 *
	 * @param json
	 * @return
	 */
	private List<Object> parseListInternal(String json) {
		List<Object> list = new ArrayList<Object>();
		json = trimLeadingCharacter(trimTrailingCharacter(json, ']'), '[');
		for (String value : tokenize(json)) {
			list.add(parseInternal(value));
		}
		return list;
	}

	private Object parseInternal(String json) {
		if (json.equals("null")) {
			return null;
		}
		if (json.startsWith("[")) {
			return parseListInternal(json);
		}
		if (json.startsWith("{")) {
			return parseMapInternal(json);
		}
		if (json.startsWith("\"")) {
			return trimTrailingCharacter(trimLeadingCharacter(json, '"'), '"');
		}
		try {
			return Long.valueOf(json);
		} catch (NumberFormatException ex) {
			// ignore
		}
		try {
			return Double.valueOf(json);
		} catch (NumberFormatException ex) {
			// ignore
		}
		return json;
	}

	private Map<String, Object> parseMapInternal(String json) {
		Map<String, Object> map = new LinkedHashMap<String, Object>();
		json = trimLeadingCharacter(trimTrailingCharacter(json, '}'), '{');
		for (String pair : tokenize(json)) {
			String[] values = trimArrayElements(split(pair, ":"));
			String key = trimLeadingCharacter(trimTrailingCharacter(values[0], '"'), '"');
			Object value = parseInternal(values[1]);
			map.put(key, value);
		}
		return map;
	}

	// append start
	private static String[] split(String toSplit, String delimiter) {
		if (toSplit != null && !toSplit.isEmpty() && delimiter != null && !delimiter.isEmpty()) {
			int offset = toSplit.indexOf(delimiter);
			if (offset < 0) {
				return null;
			} else {
				String beforeDelimiter = toSplit.substring(0, offset);
				String afterDelimiter = toSplit.substring(offset + delimiter.length());
				return new String[]{beforeDelimiter, afterDelimiter};
			}
		} else {
			return null;
		}
	}

	private static String[] trimArrayElements(String[] array) {
		if (array == null || array.length == 0) {
			return new String[0];
		} else {
			String[] result = new String[array.length];

			for (int i = 0; i < array.length; ++i) {
				String element = array[i];
				result[i] = element != null ? element.trim() : null;
			}

			return result;
		}
	}


	private List<String> tokenize(String json) {
		List<String> list = new ArrayList<>();
		int index = 0;
		int inObject = 0;
		int inList = 0;
		boolean inValue = false;
		boolean inEscape = false;
		StringBuilder build = new StringBuilder();
		while (index < json.length()) {
			char current = json.charAt(index);
			if (inEscape) {
				build.append(current);
				index++;
				inEscape = false;
				continue;
			}
			if (current == '{') {
				inObject++;
			}
			if (current == '}') {
				inObject--;
			}
			if (current == '[') {
				inList++;
			}
			if (current == ']') {
				inList--;
			}
			if (current == '"') {
				inValue = !inValue;
			}
			if (current == ',' && inObject == 0 && inList == 0 && !inValue) {
				list.add(build.toString());
				build.setLength(0);
			} else if (current == '\\') {
				inEscape = true;
			} else {
				build.append(current);
			}
			index++;
		}
		if (build.length() > 0) {
			list.add(build.toString());
		}
		return list;
	}

	// plugin util
	private static String trimTrailingCharacter(String string, char c) {
		if (string.length() > 0 && string.charAt(string.length() - 1) == c) {
			return string.substring(0, string.length() - 1);
		}
		return string;
	}

	private static String trimLeadingCharacter(String string, char c) {
		if (string.length() > 0 && string.charAt(0) == c) {
			return string.substring(1);
		}
		return string;
	}

}
